The dip tube is conventionally made of a polymeric material which is colourless, transparent and can easily be extruded in the form of tubes of small dimensions. Furthermore, the materials used for said tube have to exhibit mechanical properties suitable to allow them to be joined to the pump body at high speeds, and have to exhibit sufficient resilience to resume a substantially straight configuration after having been wound around a storage reel. For example, the materials used according to the prior art are made of polyolefin, of the polypropylene or polymethylpentene (TPX) type.
For aesthetic reasons, perfumers want the dip tube to be invisible, because otherwise it would mar the appearance of the bottles.
In order to make these tubes invisible in the solution, for perfume products, it is known to make them from a fluoropolymer-based material having a refractive index close to that of the solution. It is also necessary for the method for transforming them to provide a crystallinity of less than 13%. These fluoropolymers are not only costly and not readily available (one single supplier of these materials worldwide), but also present a health risk. The fluorine migrates into the liquid and becomes inhalable when sprayed by a dispensing system, and therefore comes into contact with the mucosa of the respiratory system. Tubes made of fluoropolymers are difficult to handle owing to their electrostatic effect which attracts dust, other particles and their packaging film. These tubes also have a mechanical performance which is poorer than that of fluorine-free polyolefin tubes. They retain the curves or bends from the assembly processes or from transport.
There is therefore a need for a bottle which comprises a dip tube which has features which contribute to making the dip tube invisible in a solution and which does not have the drawbacks mentioned above.